The present invention relates to a coating method, and more particularly to a curtain-film type coating method which is used to apply a photographic layer (for example, a photosensitive silver halide emulsion layer) of a photographic material.
As a curtain-film coating method of applying a photographic layer of a photographic material, there have been disclosed a method in which a guide rod is moved in the width direction of a freely falling curtain of coating film (see U.S. Pat. No. 3,632,403), a method in which the width of a contact surface between a guide rod and a freely falling curtain of coating film is made to correspond to the thickness of the freely falling coating film (see Japanese Patent Publication No. Sho. 61-245862), and other methods.
However, according to the first conventional method mentioned above, a problem arises in that the freely falling curtain of coating film cannot be stabilized, thereby causing a "neck-in" (e.g., a coating solution leaves an edge guide at the two ends of the falling curtain of coating film, and the falling of coating film results in being narrow in the width direction) to occur at a position located above the lower end of an edge guide.
In the second conventional method, although the formation a thick coating is minimized in portions on the film near the two ends of the coating film, formation of a thick coating inwardly of this portion and formation of a thick coating in the inside portion (e.g., a central portion) of the film in the width direction thereof still cannot be prevented.
That is, in the conventional curtain-film coating method, due to the above-mentioned poorly coated portion of the film and increased thickness of the second-mentioned thick coating, a wider, unevenly coated portion is often produced at the two ends of the film in the film coating direction (e.g., in the film width direction) as compared to other film coating methods.